3

FIELD TEST

to consume around 720 mA, of which the left motor
(when looking face to face with the car) pulls 445 mA,
whereas the right motor pulls only 285 mA, so this
may cause a bias in the steering.

ELECTRONICS
Firstly, the soldering for the circuit board is very poor:
for the motor connections the solder was barely on
the correct part of the board, and there was evidence
of the wiring being deformed due to excess heat, so
this would be a great candidate for resoldering. That
aside, the circuit board is packed with components,
but the most important is the X2455 IC that acts as
a 2.4 GHz radio receiver and decoder. The X2455 is
connected to an antenna and receives radio signals
from the controller, which it interprets and then sends
the correct response to the two CP2119 H-bridge
motor controllers that then rotate the motors in the
required direction. Despite being a common board
found in Nikko products, not much is known about
the CP2119 motor controller; in fact, the nearest data
sheet we could find was for an RZ7889 and this is
for a motor controller that works between 3 V and
15 V with a peak output current of 5 A. Should we
wish to replace the electronics, then a suitable motor
controller would be the L298 series as this can handle
up to 4 A of current, but don’t be tempted to use
the on-board 5 V regulator to power a Raspberry Pi /
Arduino as this is not suitable and could cause issues.
If you haven’t got an L298, then at a push a DRV8833
could be used but this has a peak output of 2 A, so
the startup current of the motors means that you are
pushing it past its limits. No matter what choice of
controller, the existing 7.2 V battery can be reused.
Removing the circuit board is simple: it’s held in place
by a friction fit and the wires soldered to it. There is
plenty of space for an Arduino / Raspberry Pi Zero or
other small controller boards and this would make an
instant deadly robot!

RADIO CONTROLLER

Held together with simple clips, the controller is a

cheap plastic shell offering two inputs, each with only a

forward and backward control option. They are simply

covering momentary switches, those that are used on

breadboards, and the user merely mushes the plastic

of the controller to the button. We see a 2.4 GHz radio

transmitter that relays the controls to the X2455 in the

car. The controller is powered by three AAA batteries

and is a generic unit used across the Nikko range.

CONCLUSION

The car offers plenty of scope for hacks. It can be quite

useful as a donor machine for a Robot Wars / Pi Wars

competition thanks to a great battery and space to

contain your own electronics. Build quality is decent and

there is easy access thanks to using a common type of

machine screw. The tank tracks offer stability over many

different terrains.

This is a fun platform to hack around with and

quite cost-effective when compared to other robot

donor candidates.

UNUSED PARTS

So you’ve replaced the existing electronics with

something else, but what can you do with the old X2445

and the CP2119 on the old board? Well, now you have a

simple 2.4 GHz radio receiver which can be used to build

your own radio-controlled vehicle or project that can

be remotely triggered using the electronics found in the

controller. Based on the 4.5 V power source required for

the controller, an Arduino or other 5 V logic board could

be used to simulate the button push and be used as a

remote trigger. Waste not, want not!

Above

Removing the circuit

board is simple, and

it leaves us enough

space to insert a

small Arduino, Pi

Zero or other control

board along with a

motor controller

Below

A great board that

can be repurposed

for other projects.

It combines a radio

receiver and motor

controller to enable

the user to control

the car